Ukraine’s shaky truce has been rattled further as warring rivals traded blame over the bloodiest day in the restive east since a ceasefire was signed on September 5.

Gunfire erupted around the airport in the main rebel-held city of Donetsk on Monday, a day after six civilians were killed in shelling near a market, and international observers came under fire.

Government forces and pro-Russian separatists accused the other of violating the ceasefire, the first backed by both Kiev and Moscow since fighting erupted across Ukraine’s industrial heartland in April.

Despite the surge in violence, President Petro Poroshenko unveiled legislation offering parts of the separatist east limited self-rule for three years, under the terms of the truce signed in Minsk.

The proposals would also extend Russian-language rights in the Donetsk and Lugansk regions, allow them to strengthen ties with neighbouring Russia and to hold local elections in November.

Poroshenko insisted his proposals guaranteed “the sovereignty, territorial integrity and independence of our state”, although rebel leaders have said they still want nothing less than full independence.

Kiev also plans to offer amnesty to some separatist militants as part of the peace plan aimed at halting a conflict that has cost more than 2,700 lives and sent at least half a million fleeing their homes.

The legislation is expected to be submitted to parliament on Tuesday, when politicians are also set to ratify an agreement for closer trade ties with the EU which Russia opposes.

Poroshenko has called the planned simultaneous ratifications by the Ukrainian and European parliaments a “historic moment” that will define his country’s westward-looking future.

The decision by his predecessor, Kremlin-backed Viktor Yanukovych, to spurn the same EU pact set off months of street protests that led to his ouster. Russia retaliated by annexing Crimea and backing the eastern uprising.

However, in what some see as a concession to Moscow, a free trade deal under the pact with the EU will be delayed until 2016.

On the ground, tensions were still high after Sunday’s violence, which left an unconfirmed number of soldiers dead or injured.

“The government in Kiev is only using the ceasefire to regroup its forces and attack us again,” the “prime minister” of the self-declared Donetsk People’s Republic, Alexander Zakharchenko, told reporters.

“We will not allow that,” he said.

Kiev in turn accused the pro-Russian separatists of firing on Ukrainian positions around the airport, which is still in government hands after a fierce battle in May.